Immune response to platelet transfusions.

Purpose of review: Platelet transfusion can have a significant immunological impact, exposing the recipient to alloantigens on the surface of platelets and contaminating leukocytes, a dynamic range of soluble immune mediators, and donor platelets that can directly and indirectly contribute to the inflammatory profile of the recipient. Here, we will review recent developments in our understanding of the mechanisms regulating the immune response to platelet transfusion.

Recent findings: Using animal models, much has been learned about the mechanisms regulating the alloimmune response to platelet transfusion and how this response is shaped by the underlying health of the recipient. There is also a growing appreciation of the active role platelets play in immunity and their impact on the recipient immune system and transfusion outcomes, and how these immunological profiles are shaped by product collection, processing, and storage practices.

Summary: While platelet transfusion carries significant benefit to a wide range of patients, it carries risk of alloimmunization and other immune-mediated adverse reactions. Further characterization of the mechanisms regulating these outcomes can lead to new interventions to prevent alloimmunization and help to identify which platelet products are best suited to different patient populations.